If Trump is dropped...

[ag]

There are also state deadline laws for replacements and ballot access. At some point it would be too late to take his name off.

Plus, in some states the ballots are printed soon (early Sept. I guess) so they can be sent to overseas Americans/military members.

That does not really matter. The real election is that by the electoral college. As long as the Republican electors are instructed to vote for the correct nominee, there is no problem, even if the original nominee drops out in early December.